456 Responses to “A warming pause?”

While I think it’s important to point out that the supposed lull or pause in warming is a result of the Hadley data excluding the fastest warming region on the planet, I think it’s also important to be clear that, against a background of long-term warming, an occasional decade of no warming or even slight cooling is also 100% consistent with the expected global warming trend, as pointed out in the recent GRL paper by Easterling and Wehman (doi:10.1029/2009GL037810).

That way, if and when there is a genuine pause in warming, you won’t have people pointing back to posts like this and saying, “But you said…”

One objection to this from ‘skeptics’ will be: “OK so perhaps global average temperature is still rising but it’s nothing to do with human activity, it’s all due to the PDO” [or the NAO or some other long-term natural feature of ocean circulation]. They’ll say it would have happened anyway, and is nothing unusual in the context of natural climate fluctuations. Is there a simple way to test that claim?

Once again, RealClimate takes an issue that is being dragged through the media as a big deal and shows — in a simple and easily digestible way — that they have it dead wrong.

As for #1 Michael Le Page’s comment, they specifically DO address that in the post. They say that a decade of cooling is not a big deal amidst a long-term anthropogenic warming trend. It’s just not happening now.

As for #2 Icarus’ comment, they do point out that natural factors should be producing a cooling at the moment, and that the warming that we are seeing is what is predicted from anthropogenic greenhouse warming.

These questions are answered above. Nice work Stefan. I’ll likely be posting a link to this on my blog as well.

Here’s an interesting graph that illustrates the topic somewhat, albeit only in the short term. I have added trend lines to woodfortrees standard example, “All Four Main Temperature Series for the Last Decade”, and the upward trends are clear, if slight.

Given our inablity to predict in the short term, we will have to wait, obviously, but as a sneak peek, provided temps don’t move significantly, if you shave off so much as 9 months the almost-decade now looks like:

I get it that the concern is about the long-term trends and whether they have predictive value, but it would be wise, I beleive, to acknowledge that something is going on in the short term, rather than say “Don’t look at these graphs. They mean nothing!” Unless, of course, you are willing to say, “Don’t look at those short-term arctic sea melt graphs. They mean nothing!”

One other question for the experts… Any idea why the NCEP reanalysis shows only a slight (if any) warming in west-central Greenland while the GC-Net (Greenland Climate Network) shows significant warming there? The GC-Net was geared specifically at filling gaps over Greenland. It doesn’t help if we don’t use the data.

It’s futile, stefan. Any time the current year is not the warmest year on record, somebody will try to pick the previous record high as a starting point and convince themselves that warming stopped at the previous high.

They can do this even with GISS data that includes the Arctic; they could have done this at multiple times in the past (where, with hindsight, we can clearly see the long-term trend amidst the noise), and they will likely do it at multiple times in the future.

Here’s an interesting graph that illustrates the topic somewhat, albeit only in the short term. I have added trend lines to woodfortrees’ standard example, “All Four Main Temperature Series for the Last Decade”, and the upward trends are clear, if slight.

Given our inability to predict in the short term, we will have to wait, obviously, but as a sneak peek, provided temps don’t move significantly, if you shave off so much as 9 months the almost-decade now looks like:

I get it that the concern is about the long-term trends and whether they have predictive value, but it would be wise, I believe, to acknowledge that something is going on in the short term, rather than say “Don’t look at these graphs. They mean nothing!” Unless, of course, you are willing to say, “Don’t look at those short-term arctic sea melt graphs. They mean nothing!”

The simple solution for you, Icarus, is that the PDO and the NAO and all the other natural features of the climate system have been underway for thousands of years but don’t show the kind of warming we’re currently seeing.

IOW, if what we were seeing for warming now were natural variation due to “X” we’d have seen this sort of variation many times before. We haven’t. Therefore, current warming can’t be natural variation.

Is ’87 – ’96 the best example you could give of the flat or cooling trends that are nothing special and have happened before repeatedly? Anyone who takes more than a passing interest in these issues knows that that period was significantly affected by a major volcanic eruption, whereas the last decade has not. Apples and oranges.

Most timely appropriate piece, I suspect September 2009 to be impressively warm as well. Observing the sun almost on a daily basis, as every “sun is warming advocate” should do, reveals AGW by the lack of solar activity when compared with current warming trends or data. Also by observing sun disks expand within the Hadley “hole”, year by year, ever so consistently, a completely different method of analyzing Arctic atmospheric temperature as a whole
reveals the same results as NASA GISS. So skeptics have always looked kind of silly, amateurish, and not worthy of challenging anything unless they come up with evidence (actually working in the field) disproving data acquired by 2 methods agreeing on the same warming. Looking at local Arctic Glaciers big and small, the casi totality of them receding or disappearing combined Sea Ice extent at all time lows, 2 other solid observations confirm again the 2 previous methods cited above. THere is no point arguing with a skeptic claiming recent cooling, however there is a duty to report, to others what is going on. Recent cooling
is a myth at the detriment of reality…

For beginners: RSS September 2009 is 0.476C+, up from 0.270C plus. The only warmer September per RSS record was in that faithful year 1998 showing 0.498C+, when hallelujah, global ‘Aint True’ deception began. By their logic that’s 0.2C cooling per century, still, see it is not warming ;P

PS. Dr. Roy’s superior UAH algorithm showed 0.432C+ for September 1998. Would he be able to stay below that, or would he report a higher number for last month?

I think the point to most denials of Global Warming at the moment has to do with the general mildness of the weather in big media cities more than anything else. For example, New York and Washington have had a mild time of it this year. Calamities have been happening elsewhere in the country which could easily be secondary effects of warming, and to those of us who have paid attention, the mildness has been exceptional to the point of comment. But those who do not pay attention to anything but their own comfort, and live in exceptionally unscientific bubbles, can pretend normalcy for the time being. Maybe I’m just being cynical though.

@stefan: ‘If we want to relate global temperature to global forcings like greenhouse gases, we’d better not have a “hole” in our data set. … Hence the GISS data are clearly more useful in this respect, and the supposed pause in warming turns out to be just an artifact of the “Arctic hole” in the Hadley data’.

When is data data? There are Arctic holes in the instrumental records for both GISS and Hadley. The difference is that GISS fills its hole with estimates. Wouldn’t it be equally valid to say that the supposed continuation of warming is just an artefact of GISS’s extrapolation? (Or even, to borrow your analogy, that the GISS bank account is padded with Monopoly money?) I’m not saying that GISS’s continued warming is bogus. Ditto Hadley’s hiatus. I’m just puzzled by your apparent assumption that a temperature-record-plus-clever-maths-infill is necessarily more valid than a more straightforward temperature record. Surely both approaches have merit?

[Response: In essence GISS fills the hole with data from surrounding areas (and there is good evidence to support that this is reasonable, see Rasmus’ plot of the NCEP reanalysis shown in Fig. 2), while Hadley assumes the Arctic behaves like the global mean. I believe the latter is an unreasonable assumption. -stefan]

No, resistance is not “futile,” tharanga! I for one have been significantly educated by this post and will spread the knowledge to everyone I talk to about the subject. Great post — timely, crucial in fact, in a context where even Revkin over at the New York Times speaks of a “plateau in temperatures” over the last decade as if it were a plain fact (http://www.nytimes.com/2009/09/23/science/earth/23cool.html?scp=2&sq=decade%20no%20warming%20climate&st=cse) and ponders its impact on policymakers rather than challenging the “plateau” claim itself.

My emphatic thanks to the makers of this post and this whole blog. Please: don’t give up on repeating yourselves, answering old fallacies, refreshing the arguments. There are always new people coming along who need to hear the science in an up-to-date form. The denialist fallacies will be trotted out annually in new clothes for as long as the Earth spins and need to be stripped bare all over again. It is a wearisome chore, probably, for scientists with real work to do, but it is an _indispensable_ contribution to the public discourse on climate.

Using paleoclimate to rule out ‘natural variability’ due to ocean dynamics as the cause of global warming is a poor choice. You’ll just end up in endless arguments about tree rings, as the sceptics don’t accept any hockey-stick style reconstructions, anyway.

Better to point out positive evidence that the greenhouse gas mechanism is indeed at hand. There are several physical fingerprints of the mechanism, and the models are pretty well validated.

A sustained 30-year surface warming simply due to redistribution of heat in the oceans would surely leave some observable fingerprints: the heat has to come from somewhere. Icarus: don’t let your sceptics use ‘natural variability’ as a magical hand-waving exercise that can explain any and all observations. Require them to explain a mechanism, quantify it, and validate it against observations.

Ask the skeptics how natural events such as NAO, PDO, etc. have caused stratospheric cooling and tropospheric warming. :)

#8:

The skeptics will claim that the hockey-stick is broken so that PDO, NAO, etc., are not being accurately displayed. Nonsense of course, but then just ask how the stratosphere is cooling due to these things. :)

Is it not the case that they have a “hole” in their dataset because there are few observations in the Arctic? That being the case, the warming in the GISS dataset is reliant on a very small number of data points, which makes them potentially unreliable due to the possibility of their being spurious trends due to local changes that aren’t representative of the Arctic as a whole. [Though the record minimums of sea-ice coverage are an excellent confirmation of this warming trend being real]

Also, there are no error bars on your graphs! On the Hadley website they show error bars, the biggest contribution to which is sampling issues [because of lack of spatial data coverage]. Surely there must be a way for you to construct an error estimate of your interpolation – perhaps by testing it with model data? I suspect that, with appropriate error estimates, it wouldn’t be possible to conclude that the two records are significantly different.

One thing we can be certain of is that, should the Arctic region experience a temporary cooling “trend” over the next ten years, resulting in the GISS record exhibiting a lower global trend in temperature than the Hadley record, then the climate “sceptics” will be quoting GISS and rubbishing Hadley/CRU when they are trotting out similar arguments in 2019.

I went to the “The Wood for trees” interactive graphs and use HADCRUT3 variance adjusted Global mean data from the time period 1997 to 2009 and it shows a flat trend line from at .4C. Thats over the last 12 and 3/4 years.
FYI
Ed

The authors analyze 20th century surface warming and attributions to tease out anthropogenic greenhouse forcing contributions and natural variation. The conclude that the anthropogenic forcing has been (and continues to be) a monotonic, accelerating warming during the 20th century. This has been modulated by natural contributions, especially ocean current effects on surface temperature, the net contribution of which to 20th century warming has been close to zero. These authors remark on the possibility that natural variation might result in a suppression of surface warming for a period. However they also point out that “However, global warming could likewise suddenly and without any ostensive cause accelerate due to internal variability”.

It’s also worth pointing out that while the surface warming may respond to some periods of ocean current-induced heat redistributions that temporarily suppress or enhance the surface temperature, the continuation of global warming is apparent in the continuation of heat uptake into the worlds oceans.

A recent analysis has just been published that indicates a continuing heat uptake at a rate near 0.8 W.m-2 right through 2008. Obviously this heat penetrating the oceans will eventually have a warming influence on the surface. So there isn’t really a warming pause at all if the world is considered truly globally!

Excellent post – once again RC delivers a concise and clear summation of the science.

Since I’m a layman, could I ask a few quick questions that someone might shed some light on for me: is it correct for me to say that the GISS data doesn’t have the actual measurements from the arctic, but rather adjusts its findings based on its existing measurements? If so, is that a process of interpolation or extrapolation (or does that even matter)? Further, does GISS have a larger rate of error than the Hadley results due to the process of adjusting for acrtic temperature? Does that error rate significantly alter the results you’ve shown us above?

As some readers may know, misunderstandings around this topic are a staple at DeepClimate.

I discussed the confusions inherent in Andy Revkin’s article mentioned above, as well as the misinterpretations and distortions around Mojib Latif’s presentation at the recent World Climate Conference in Geneva. In the latter case, Fred Pearce’s confused New Scientist piece started the ball rolling.

And, of course, then the PR disinformation spinmeisters like Marc Morano took over and spewed out their falsehoods. Next thing you know you’ve got George Will and Lorne Gunter declaring the end of global warming and “quoting” Mojib Latif in support.

The number of commenters I’ve encounterd who insist that there is a pause in global warming (in the face of all the statistical evidence to the contrary), and then point to the Revkin in NYT and Fred Pearce in New Scientist articles as proof, is really depressing.

Until the popular science press gets it right, this nonsense will continue.

How does this fit in with Professor Mojib Latif from the Leibniz Institute of Marine Sciences at Keil University, who has stated that from recent research he has conducted he has had to conclude that global warning has ceased, that the planet is currently cooling and will likely continue to do so for another 20 years.

I’ve heard that the satellites do not observe the poles well, is this the reason for lower satellite trends? For that matter, anyone know the reason for the difference between the UAH and RSS trends? That’s bigger than the difference between the surface station trends or between RSS and Had-CRU, (over a 30 year period) and I have no idea what the difference is between these data sets.

Phillip, that is simply not what Latif said. You might find Deep Climate’s posts on the topic interesting (linked above your post) as he replays the telephone game that has been played with Latif’s words. All he says is that it is possible for natural variability to create a one or two decade cooling “trend” within a longer term warming trend, he certainly did not predict cooling in the next decade.

“In the ERSST version 3 on this web page we have removed satellite data from ERSST and the merged product…Although, the satellite data were corrected with respect to the in situ data as described in reprint, there was a residual cold bias that remained as shown in Figure 4 there.”

It seems to be a minor issue, but do GISS global mean temperature products rely on the same satellite data that NOAA is reporting has a cool bias? Do you agree with this analysis and does GISS have plans to address it?

That’s an odd one Philip considering that Latif has just recently published a paper in which he predicts an extremely large surface warming (around 0.5 oC) in the period around 2010-2030 (see Figure 4 of:

The Forbush decreases are too short-lived to have a lasting effect on the climate…

But then:

The director of the Danish National Space Institute, DTU, Eigil Friis-Christensen, was co-author with Svensmark of an early report on the effect of cosmic rays on cloud cover, back in 1996…”the current climate models used to predict future climate are lacking important parts of the physics.”

What’s needed is a measure that includes ocean heat content as well as the SST and air temperatures. If you include ocean heat content as part of the overall energy budget (overall global warming), then even with the Hadley data you get global warming during the last decade.

I get it that the concern is about the long-term trends and whether they have predictive value, but it would be wise, I believe, to acknowledge that something is going on in the short term, rather than say “Don’t look at these graphs. They mean nothing!” Unless, of course, you are willing to say, “Don’t look at those short-term arctic sea melt graphs. They mean nothing!”

#15 Mark: I am referring to the NCEP figure above. If you look at west-cental Greenland, it is green to yellow, showing little warming. The GC-Net data show a rapid warming in that area (see: http://bprc.osu.edu/~jbox/pubs/Box_et_al_J_Clim_2009.pdf for example). We can also look at ballon soundings: http://bprc.osu.edu/%7Ejbox/pubs/Box_and_Cohen_GRL_2006.pdf or model output. Or, as #20 Mauri Pelto points out, look at the mass loss, glacier acceleration, and grounding line retreat in that area. It seems that it should be a big red spot on that map, not an unremarkable light green to yellow. I am curious as to why these data don’t seem to match. Anyone?

Richard Kerr of Science Magazine has picked up the no warming meme that Revkin published in the Times over a week ago. I gather the story started in England as Deepclimate notes above. Joe Ramm at Climate Progress handily debunked the Revkin article and commenters including me put up the link to the debunking in the Times’ comment section but Revkin did not correct or retract his article.

Reporters have done a miserable job of explaining the science of climate change. They have made it easy for right wing apologists like George Will to peddle disinformation to the public. Will points to Revkin and washes his hands of responsibility for getting the science wrong.

Perhaps you should forward this post to Andy Revkin. Maybe he will listen to you.

I have written the editor to complain about the reports lack of attention to the issues presented in Stefan’s post and the issues I raised in my previous comment. I feel it is irresponsible for Science to publish such an incomplete and misleading piece just weeks before the Copenhagen conference.

I hope some of you will join me in expressing your concern to the editors of Science.

It is also my hope that Gavin and Stefan have penned a comment for Science.

#27 Philip – he never said, and you have either willfully or naively echoed something Morana picked up and spun. What Latif said was “It may well happen that you enter a decade, or maybe even two, when the temperature cools, relative to the present level.” He did not conclude “that global warning has ceased, that the planet is currently cooling and will likely continue to do so for another 20 years” as you stated.

Basically what Latif said is the same as what Stefan said in this post “Even under conditions of anthropogenic global warming (which would contribute a temperature rise of about 0.2 ºC over this period) a flat period or even cooling trend over such a short time span is nothing special and has happened repeatedly before (see 1987-1996).”

Jari #22: by the meteo stations surrounding the Arctic. Essentially what happens compared to Hadcrut is, that these circum-arctic stations are upweighted and made to represent the Arctic as a whole, not just the rim.

I said:
“Until the popular science press gets it right, this nonsense will continue.”

It also needs to be added that the mainstream press needs to cry foul on the spin doctors. Loudly and unambiguously.

How is it that Marc Morano can utter blatant falsehoods day after day, or CEI or Patrick Michaels, or George Will and Glenn Beck for that matter, and Andy Revkin says nothing?

And, I’m sorry, but the respectful coverage of Steve McIntyre, serial utterer of false unfounded accusations of malfeasance against the world’s top climate scientists, is even worse. But that’s another thread, I suppose.

The trouble is when people make vague statements, such as Prof Latif saying “It may well happen that you enter a decade, or maybe even two, when the temperature cools, relative to the present level.” (from the link given). So how are people to interpret “may well happen”? Is this the same as “likely” as defined by the IPCC, i.e. a >66% probability of occurrence? It “may well happen” certainly suggests >50% probability of occurrence to me. Am I wrong?

The misunderstanding you are talking about has been discussed. I was in the room in Geneva when he discussed the issue. He did not state we are going to cool. He discussed natural variability and potentials in the context of dcadal predictability and potential. If you listen to his words you can hear his contexts. He is talking to scientists of course. He discusses challenges. It is easy to take words out of context, which is what a lot of people did, unfortunately. It is important to understand that he is discussing decadal predictability, not the AGW climate trend.

Phillip Bratby @43, yes, you are wrong. Latif said “may well happen” in the context of a public oral presentation, not in scientific paper. He was saying exactly what Stefan is saying in this post: that even during a period when there is an long term upward warming trend there will be times when there may well be a shorter term when natural variability temporarily cancels out or even overcomes that underlying warming trend. Igor Samoylenko @36 provides just such a an example from the recent record up thread.

1. How long does a change in the solar brightness get reflected in, say, the GISS surface temperature analysis (or other indicators of climate)? I ask because in this blog post Stefan seems to imply that the record low brightnesses measured over the past 3 years should have been reflected in the GISS data by now, and my understanding that the timescale for such changes in solar forcing is longer.

2. The earth’s orbit is elliptical, being ~3% closer to the sun at perihelion than at aphelion. This would seem to cause an annual 1% variation (via the inverse-square law) in the solar energy incident at earth, which is an order of magnitude stronger than the 0.1% variation in solar luminosity over the course of the 11-year solar cycle that is mentioned here. What response does the climate have to this (stronger but more faster varying) annual variation in incident radiation from the sun?